The ability of ice-flow indicators to record complex, historic deglaciation events, Burroughs Glacier, Alaska

Known changes in ice-flow direction during a 100-year interval have been used to evaluate how well ice-flow indicators record complex deglaciation events. At Burroughs Glacier, nunataks emerging from a thinning Neoglacial ice mass and differential ice-surface lowering caused by calving ice margins have produced major changes in ice-flow direction sincc 1892. Cross-cutting striae with angles of divergence of up to 105' reflect the past range of flow directions in the area. Striae from the oldest flow events are deepest, and striae from some late-stage flow events are missing. This may be caused by overprinting during late-stage reversals in the direction of ice movement. The orientation of flutes and surficial bullet boulders reflects the final ice-flow direction, but boulder orientations are less clustered than flute orientations. Surficial till pebble fabrics are weakly to moderately developed, but till fabrics vary with depth and record ice-flow direction changes with time.